Born in Essex, and brought up by a single mother on a council estate, he was educated at Brentwood School (where he took the name "Jack" after the 14th century peasant leader Jack Straw) and the University of Leeds. During his time as president of the Leeds students' union, and subsequently of the National Union of Students, he was regarded as a radical on issues of social equality and race, though he opposed drugs. He qualified as a barrister and practised criminal law before becoming a political adviser to Labour ministers in 1974-77 and then a television journalist.

He is Member of Parliament for Blackburn[?], a seat he won after the retirement, in 1979, of Barbara Castle (for whom he had worked as a political advisor when she was social security minister), and is honorary president of Blackburn Rovers F.C.[?]. In the 1980s he was an opposition spokesman on economic affairs and later on the environment before becoming Shadow Education Secretary in 1987, Shadow Environment Secretary in 1992 and eventually Shadow Home Secretary.

As Shadow Home Secretary between 1994 and 1997, he was at pains not to allow the Labour Party to be painted as "soft on crime", and developed a reputation as being even more authoritarian than the Tory Home Secretary Michael Howard, condemning "aggressive beggars, winos and squeegee merchants" and calling for a curfew on children.